Steel is the main cost driver when creating offshore wind farms. In order to minimize the stress concentration factor and be able to reduce the need for steel, design and engineering giant Rambøll asked cable and pipe transit specialist Roxtec to design an oval seal. The result is nothing but extraordinary: for the wind farm, the steel savings reach 1,000 tons.
“We use oval seals in all our projects now, and we will continue to use them to save tons of steel in all our future projects,” says structural design engineer Christian Lønne of Rambøll.
Danish Rambøll is a global player in many industries, including offshore wind power. The group has provided detailed design consultancy in more than 60 offshore projects with thousands of monopiles and jacket foundations.
Christian Lønne is responsible for structural design management at Rambøll. He makes sure the primary and secondary steel designs correspond to the needs of the other parts of the project. When overseeing full interconnectivity, he always encounters the challenge of sealing tight around everything from platform electrical cables to ICCP systems and ventilation pipes.
It was natural for Rambøll to approach Roxtec with their request for oval seals instead of round or rectangular ones. The objective was to be able to save steel in the heavy transition pieces by reducing the stress and risk of fatigue. The sealing experts at Roxtec listened to the thoughts and ideas and developed a perfect solution. The oval seal passed several tests before delivery.
“It is pure mathematics,” says Christian Lønne. “Stress forces choose better ways if you have an oval opening instead of a round opening in the structure. By changing seal type, we were able to save 35 percent of the steel in that section of the transition piece.”
A winning feature
“We will recommend using oval seals for all future projects”, says Christian Lønne. “The solution has even been a contributing factor for us winning big offshore wind farm contracts.”
Roxtec cable and pipe transits do not only deliver certified protective performance for long-term operational reliability. They also contribute to efficient usage of valuable resources such as steel. It is also easier to roll out renewable wind power when you can use lighter structures.
Success stories within power
Taizhou ±800kV converter station, China
State Grid Corporation of China, SGCC, uses Roxtec BG™ solutions in their HVDC transmission projects.